Display apparatuses of non-self-light-emitting type, e.g., liquid crystal display apparatuses, perform displaying by utilizing light which is emitted from a lighting device that is called, a backlight. Although cold cathode fluorescent lamps (CCFL) have mostly been used as the light sources in lighting devices, use of light-emitting diodes (LED) has recently been gaining prevalence.
A lighting device of a display apparatus that performs color displaying typically emits white light. Generally speaking, white light contains light of a plurality of colors within the wavelength region (380 nm to 780 nm) of visible light. For example, white LEDs combining a blue LED chip that emits blue light and a fluorescent material that emits yellow fluorescent light upon receiving blue light are widely in use. Moreover, white LEDs combining a blue LED chip and a fluorescent material that emits fluorescent light of red and green are also in use. Furthermore, white LEDs combining three LED chips respectively emitting red light, green light, and blue light are also in use. A white LED (also called a “pseudo white LED”) in which one LED chip and a fluorescent material are combined is referred to as a single-chip type, whereas a white LED in which two or more LED chips are combined may be referred to as a multi-chip type. In the present specification, an LED chip is meant to be a light-emitting element (light-emitting portion), whereas an LED is meant to be a light-emitting device having an LED chip(s) mounted thereon.
Lighting devices of display apparatuses can be generally classified into direct types and edge light types. With reference to FIGS. 12(a) and (b), an example of a conventional construction of an edge light type lighting device will be described. FIG. 12(a) is a cross-sectional view schematically showing a liquid crystal display apparatus 1000 including an edge light type lighting device 900, and FIG. 12(b) is an upper plan view schematically showing a substrate 930 included in the lighting device 900.
As shown in FIG. 12(a), the liquid crystal display apparatus 1000 includes the lighting device 900 and a liquid crystal display panel 1050. The liquid crystal display panel 1050 is at the front face side of the lighting device 900 (i.e., the viewer's side).
The lighting device 900 includes a plurality of white LEDs 910 and a light guide plate 920.
Each of the plurality of white LEDs 910 has a light-emitting portion 910a. The plurality of white LEDs 910 are mounted on the substrate 930. As shown in FIG. 12(b), the substrate 930 is rectangular-shaped (strip-shaped). A heat sink 980 is provided in contact with the substrate 930. The heat sink 980 allows heat generated from the white LEDs 910 to be dissipated.
The light guide plate 920 has a light-receiving end face 920a that receives light which is emitted from the plurality of white LEDs 910 and an outgoing face (upper principal face) 920b that crosses the light-receiving end face 920a. A reflection sheet 922 is provided on the opposite side of the light guide plate 920 from the outgoing face 920b (i.e., on a lower principal face 920c). An optical film 924 is provided on the outgoing face 920b side. The lighting device 900 is supported on a backlight chassis 940.
The liquid crystal display panel 1050 is held by a panel chassis 1060. The panel chassis 1060 is held by a bezel 1070.